Field
The present disclosure generally relates to the field of spinal orthopedics, and more particularly to a device for introducing a rod to a fixation system through a minimally invasive approach.
Related Art
The spine is a flexible structure that extends from the base of the skull to the tailbone. The weight of the upper body is transferred through the spine to the hips and the legs. The spine contains a plurality of bones called vertebrae. The vertebrae are hollow and stacked one upon the other, forming a strong hollow column for support. The hollow core of the spine houses and protects the nerves of the spinal cord. The spine is held upright through the work of the back muscles, which are attached to the vertebrae. While the normal spine has no side-to-side curve, it does have a series of front-to-back curves, giving it a gentle “S” shape.
Each vertebra is separated from the vertebra above or below by a cushion-like, fibrocartilage called an intervertebral disc. The discs act as shock absorbers, cushioning the spine, and preventing individual bones from contacting each other. In addition, intervertebral discs act as a ligament that holds vertebrae together. Intervertebral discs also work with the facet joint to allow for slight movement of the spine. Together, these structures allow the spine to bend, rotate and/or twist.
The spinal structure can become damaged as a result of degeneration, dysfunction, disease and/or trauma. More specifically, the spine may exhibit disc collapse, abnormal curvature, asymmetrical disc space collapse, abnormal alignment of the vertebrae and/or general deformity, which may lead to imbalance and tilt in the vertebrae. This may result in nerve compression, disability and overall instability and pain. If the proper shaping and/or curvature are not present due to scoliosis, neuromuscular disease, cerebral palsy, or other disorder, it may be necessary to straighten or adjust the spine into a proper curvature with surgery to correct these spinal disorders.
Fixation is a surgical method wherein two or more vertebrae are held together by the placement of implants to stabilize the vertebrae. Surgical treatments may involve manipulation of the spinal column by attaching corrective implants, such as rods, wires, hooks, screws, and the like, to straighten abnormal curvatures, appropriately align vertebrae of the spinal column and/or reduce further rotation of the spinal column. The correct curvature can be obtained by manipulating the vertebrae into their proper position and securing that position with a rigid system of screws and rods. The screws can be inserted into the pedicles of the vertebrae to act as bone anchors, and the rods may be inserted into heads of the screws. Two rods may run substantially parallel to the spine and secure the spine in the desired shape and curvature. Thus the rods, which are shaped to mimic the correct spinal curvature, force the spine into proper alignment.
In many cases, the fixation is augmented by a process called fusion, whereby an interbody implant is positioned in the intervertebral space between two or more vertebrae to join the vertebrae together. Bone grafts can be placed between the vertebrae and aid in fusion of the individual vertebrae together to form a correctly aligned spine.
In addition, minimally invasive surgical techniques have been used on the spine to access the spine through small incisions. Minimally invasive spine surgery offers multiple advantages as compared to open surgery. The advantages may include minimal tissue damage, minimal blood loss, smaller incisions and scars, minimal post-operative discomfort, and relative quick recovery time and return to normal function.